European Patent Application Publication Number 0 475 213 A1 published 18.03.92 Bulletin 92/12 (hereinafter "EP Application") based on U.S. patent applications Ser. Nos. 578,697 filed Sep. 4, 1990; 578,696 filed Sep. 4, 1990, and 686,956 filed Apr. 18, 1991, discloses thermal insulating glazing units having an edge assembly having low thermal conductivity and a method of making same. In general, the EP Application teaches thermal insulating glazing units having a pair of glass sheets about and sealed to an edge assembly to provide a sealed compartment between the sheets. The edge assembly includes a U-shaped spacer frame made of a material that is moisture and/or gas impervious, the spacer frame having a sealant on each of the outer surfaces of the upright legs of the spacer frame and a moisture pervious adhesive bead having desiccant therein adhered to inner surface of the spacer frame. The materials of the edge assembly are selected and sized to provide the edge assembly with a predetermined RES-value as defined and determined in accordance to the EP Application. The EP Application further discloses a thermal insulating glazing unit having three or more sheets with an edge assembly between the adjacent glass sheets.
U.S. patent application Ser. No. 08/102,596 filed Aug. 5, 1993, (hereinafter "U.S. patent application Ser. No. 08/102,596") discloses multi-sheet glazing units or thermal insulating units having one or more glass sheets spaced from and between a pair of outer glass sheets. In general, the units include the pair of outer glass sheets secured to outer legs of a spacer frame having a U-shaped cross section. On the base of the U-shaped spacer frame between the upright legs is a layer of a pliable material having a groove(s) for receiving edge portions of intermediate glass sheet(s).
Although the units disclosed in the EP Application and U.S. patent application Ser. No. 08/102,596 are acceptable, it would be beneficial to have a method of manufacturing a multi-sheet glazing unit having three or more sheets that doesn't require providing an edge assembly between adjacent sheets as disclosed in the EP application or forming a groove(s) in a layer of pliable material to receive the edge of the intermediate sheet(s) as disclosed in U.S. patent application Ser. No. 08/102,596.
U.S. Pat. No. 4,149,348 discloses multi-sheet glazing units having three or more glass sheets. In general, the units include a pair of outer glass sheets separated by a spacer-dehydrator element, or metal spacer having a generally rectangular cross sectional configuration and having a groove to maintain the intermediate glass sheet(s) between and spaced from the pair of outer glass sheets.
Although the glazing units taught in U.S. Pat. No. 4,149,348 are acceptable, there are limitations. More particularly, the spacer-dehydrator element containing desiccant is formed with a groove, and thereafter the spacer-dehydrator element has to be stored in a dry environment to prevent adsorption of moisture by the desiccant prior to its use. The use of the grooved metal spacer requires additional steps to form the spacer thereby increasing the fabrication cost of the glazing unit.
As can be appreciated, it would be advantageous to provide multi-sheet glazing units having three or more sheets and method of making multi-sheet glazing units that supplement and/or minimize or eliminate the limitations of presently known multi-sheet glazing units and methods of making them.